/*  Copyright (c) 2012 Xiaoyun Zhu
 * 
 *  Permission is hereby granted, free of charge, to any person obtaining a copy  
 *  of this software and associated documentation files (the "Software"), to deal  
 *  in the Software without restriction, including without limitation the rights  
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  
 *  copies of the Software, and to permit persons to whom the Software is  
 *  furnished to do so, subject to the following conditions:
 *  
 *  The above copyright notice and this permission notice shall be included in  
 *  all copies or substantial portions of the Software.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER  
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,  
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN  
 *  THE SOFTWARE.  
 */
package cn.kk.fluidcells;

import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.LinkedList;
import java.util.List;

public final class CellPluginsHelper {
    private static final Class<?>[] parameters = new Class<?>[] {
        URL.class
    };

    private static final FilenameFilter JAR_FILE_FILTER = new FilenameFilter() {

        @Override
        public boolean accept(File dir, String name) {
            return name.endsWith(".jar");
        }

    };

    public static List<URL> findCellPlugins(File directory) throws IOException {
        List<URL> cellPluginUrls = new LinkedList<URL>();
        if (directory.exists()) {
            File[] files = directory.listFiles(CellPluginsHelper.JAR_FILE_FILTER);
            for (File file : files) {
                cellPluginUrls.add(file.toURI().toURL());
            }
        } else {
            directory.mkdirs();
        }
        return cellPluginUrls;
    }

    public static List<URL> loadCellPlugins(List<URL> cellPluginUrls) throws IOException {
        URLClassLoader sysLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();
        URL urls[] = sysLoader.getURLs();
        List<URL> todos = new LinkedList<URL>();
        for (URL u : cellPluginUrls) {
            for (int i = 0; i < urls.length; i++) {
                if (!urls[i].toString().equals(u.toString())) {
                    todos.add(u);
                } else {
                    System.err.println("URL " + u + " already loaded");
                }
            }
        }
        cellPluginUrls.clear();
        Class<?> sysclass = URLClassLoader.class;
        for (URL u : todos) {
            try {
                Method method = sysclass.getDeclaredMethod("addURL", CellPluginsHelper.parameters);
                method.setAccessible(true);
                method.invoke(sysLoader, new Object[] {
                    u
                });
                cellPluginUrls.add(u);
            } catch (Throwable t) {
                t.printStackTrace();
                System.err.println("Could not load URL " + u);
            }
        }
        return cellPluginUrls;
    }
}
